Prognostic Value of Qualitative Splenic [18F]FDG Uptake on Baseline PET/CT in Newly Diagnosed Diffuse Large B-Cell Lymphoma

<b>Background/Objectives</b>: Accurate risk stratification at diagnosis is crucial for the optimal management of diffuse large B-cell lymphoma (DLBCL). While Fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography ([¹⁸F]FDG PET/CT) is the standard imaging modality for staging, the prognostic value of non-tumoral uptake patterns remains under investigation. Here, we aimed to investigate the prognostic significance of qualitative splenic [¹⁸F]FDG uptake on baseline PET/CT in patients with newly diagnosed DLBCL, focusing on relapse-free survival (RFS) and overall survival (OS). <b>Methods</b>: This retrospective study included consecutive patients with newly diagnosed DLBCL in a Korean cohort who underwent baseline [¹⁸F]FDG PET/CT between December 2016 and August 2023. Qualitative splenic uptake was visually assessed on maximum intensity projection images. Associations between splenic uptake, prognostic indices, and clinicopathologic characteristics were evaluated. Survival outcomes and independent prognostic factors were analyzed using Kaplan-Meier methods and Cox proportional hazards regression models. <b>Results</b>: A total of 142 patients were analyzed (43 relapsed, 58 died). Positive splenic [¹⁸F]FDG uptake was observed in 72 patients and was significantly more frequent in patients who relapsed (<i>p</i> < 0.001). Positive splenic uptake was significantly associated with inferior RFS (<i>p</i> < 0.001) and OS (<i>p</i> = 0.010). For RFS, advanced Ann Arbor stage, ECOG performance status, and extranodal involvement were also significant factors. In multivariable analysis, positive splenic uptake remained an independent predictor of poorer RFS (hazard ratio 2.175, <i>p</i> = 0.043), along with advanced stage (hazard ratio 2.872, <i>p</i> = 0.004). <b>Conclusions</b>: Qualitative splenic [¹⁸F]FDG uptake on baseline PET/CT is associated with adverse clinical outcomes in patients with DLBCL and serves as an independent prognostic factor for RFS.